New York Republicans are backing a former Long Island lawmaker to take on Democratic Sen. Kirsten Gillibrand (KEHR'-sten JIL'-uh-brand), but an economist has won enough support from party leaders to force a primary.

Bruce Blakeman, a former member of the Nassau County Legislature, will face a challenge from David Malpass, a former Bear Stearns chief economist. A third candidate, former congressman Joe DioGuardi, didn't get enough votes at the state Republican convention Thursday to get onto the Sept. 14 primary ballot.

Gillibrand was appointed last year to replace Hillary Rodham Clinton, who was named U.S. secretary of state.